Field of the Invention
The present invention relates to a liquid ejection apparatus, a liquid ejection head, and a method of supplying a liquid, and specifically relates to a liquid supply mechanism that supplies a liquid to a passage in a liquid ejection head by generating a pressure difference between a supply side and a collection side.
Description of the Related Art
Japanese Patent Laid-Open No. 2014-141032 describes that a liquid flow is generated in a liquid passage, in which an energy generation element is provided, communicating with an ejection opening of a liquid ejection head. In this way, for example, a liquid (ink) having increased viscosity around the ejection opening is discharged, and an ejection characteristic is prevented from being degraded. In the Japanese Patent Laid-Open No. 2014-141032, two types of pressure adjustment tanks, control pressure of which are set to be different from each other, in a supply path and a collection path of the liquid in the liquid ejection head respectively are used to control pressures in a liquid supply path at an upstream side and a downstream side of the liquid ejection head to be constant. Thereby, the ink flow is generated in the passage of the liquid ejection head by a predetermined differential pressure between the supply path and the collection path.
In a long head such as a line-type head, the number of ejection openings increases, and thus the supply amount of ink to the head increases. For this reason, a flow amount fluctuation or a difference in pressure loss inside the liquid ejection head, generated due to a fluctuation in ejection duty depending on printed data, etc. increases. As a result, there is concern that a negative pressure around the ejection opening greatly varies, and thus the volume of ejected liquid droplets may change, and a defect such as uneven density of an image may be generated.
For this problem, in the Japanese Patent Laid-Open No. 2014-141032, the two pressure adjustment tanks operates to generate the predetermined differential pressure between the supply path and the collection path with respect to the liquid ejection head. However, the predetermined differential pressure cannot be generated in a case where an error occurs in a resistance set for each of the supply path and the collection path, or an error in the resistance over time occurs (hereinafter these errors from set values will be referred to as “tolerances”).